The way from a wheat- to a gluten free-sourdough up to gluten free breads

The use of the sourdough is the oldest biotechnological process to leaven baked goods, and it has been proven to be ideal for improving bread texture, palatability, aroma, shelf-life and nutritional value. Even if these effects have been extensively studied for the traditional baking, few attempts have been made for producing and evaluate gluten free (GF) sourdoughs and the resulting GF breads. The aim of this study was the setting up of a GF sourdough starting from a wheat-based sourdough traditionally used for the production of Panettone, a well-known Italian sweet baked product. The isolated Lactic Acid Bacteria and yeast strains were inoculated into a GF matrix, containing corn starch, rice flour, pea isolate, hydrocolloids and fiber as main ingredients. The starter obtained was constantly and continuously propagated over a 30 days period, and its properties (number and type of microorganisms; dough consistency, pH, titratable acidity and capability to produce and retain CO2) were regularly monitored. A stable association between microorganisms (L. sanfranciscensis and C. humilis) was obtained just after the second refreshment, and the microbiological population and technological properties of the developed GF sourdough (GFSD) remained constant and satisfactory from here onwards. Only at this point breadmaking trials were performed, to compare the quality of GF doughs and breads obtained using GFSD or compressed yeast (CY), or their mixture (GFSD+CY), as leavening agents. The higher crumb hardness value obtained for GFSD-bread was probably due to its lower development during breadmaking. However, CY-bread exhibited a crumbly behavior during storage (69h, 25°C, 60%RH), that was absent in SD-bread. In general, when GFSD was used in combination with CY a synergic effect was highlighted and an improvement of the overall GF bread quality and shelf-life was achieved.